NATO members are finding it increasingly difficult to sustain their commitment to the Kosovo peace process.

By Nick Childs in London

Whatever the arguments over who won and who lost the Kosovo conflict, the NATO Secretary-General, Lord Robertson, is warning that the Alliance's efforts to safeguard peace in the region are under threat.

There are currently around 44,000 peacekeepers serving with the NATO-led force, KFOR, nearly 39,000 of them in Kosovo itself. That remains a significant commitment. But the NATO supreme commander in Europe, General Wesley Clark, contended that this was not enough, following the recent stand-off in Mitrovica. His plea for more contingents was initially rebuffed, although France, Italy, and Britain have now said they'll send limited numbers of extra troops.

NATO insists that, generally, the situation in Kosovo is under control, and is obviously far better than it was a year ago. Mitrovica, it insists, is a particular problem. But the confusion and difficulties the Alliance experienced in dealing with the recent flare-up there underlined the strains its members are under in sustaining their Kosovo commitment.

Mitrovica fuelled new concerns in the Pentagon over the risks to the 5,000-strong US contingent in Kosovo. The United States - especially sensitive about exposing its troops in the midst of a presidential election campaign - subsequently placed new restrictions on the deployment of US forces around the province. And it has emerged that all but three of the Alliance member states present in Kosovo have also done so, hindering the flexibility of the operation.

Worries about the lack of progress in establishing a stable peace have also prompted accusations in the US Congress that Washington's European allies are not pulling their weight in Kosovo, especially in terms of the civilian reconstruction effort and restoring civilian administration. This has even led to threats in the Congress to withhold up to $2 billion in supplementary funding for the US Kosovo contingent, raising at least a remote prospect of an early US withdrawal.

A year ago, the Kosovo conflict turned into a life-or-death struggle not only on the ground but also within the Alliance. It became a test of NATO's credibility, one the Alliance could not afford to lose. In the end such pressure ensured Alliance unity, but that unity was always fragile. Since then, the carping - mostly across the Atlantic - over how the air war was fought has spilled into the open. Now the much more complex mission of locking-in a long-term peace process is creating new strains, with potentially serious consequences for NATO's credibility.

The gap in perceptions across the Atlantic was further highlighted by the different reactions to recent allegations that a mole in NATO provided Belgrade with advance warning of NATO bombing missions. Washington was clearly far readier to give credence to the charge and implications that it was a European security failing. The European allies have been much more dismissive.

These frictions may be exacerbated when the Franco-German creation, the Eurocorps, takes over local command of KFOR in April. The Eurocorps' presence in terms of numbers will be very limited, and it will be operating wholly within a NATO context. But the unease felt in some circles about this move reflects a much wider US ambivalance over the development of a stronger European security and defence indentity, which - despite European protestations - many still see as a threat to NATO and the US commitment to Europe.

The Alliance may be storing up problems for the future. It's been accused of adopting a short-term approach to the problems of Kosovo and failing to produce a long-term strategy. That in part is because there are differences emerging over what Kosovo's long-term future should be, with Washington now more willing to contemplate - in private at least - an independent Kosovo, an outcome the Europeans still fear will produce a Balkans "domino" effect starting in Macedonia.

Some of the problems NATO faces are not of its own making. While the Kosovo Liberation Army, UCK, is now notionally disbanded and the United Nations in control of civil administration, in practice the UCK and its supporters wield considerable influence, in part because of the slowness of the international civil administrators to move in behind the NATO troops last June. NATO has been devoting considerable resources to trying to protect the Serb minority, and preventing the de facto partition of the province. And, in the end, the very lack of consensus on changing the UN mandate means that the international community is probably locked into Kosovo for the foreseeable future.

Nick Childs is a BBC World Affairs Correspondent who covered last year's conflict from Brussels and Kosovo.